The present invention relates to a traveling speed regulating device for a motor vehicle, which has a drive motor and a transmission controlled by an electronic transmission control device.
Travelling speed regulating devices of the above mentioned general type are widely used first of all in motor vehicles of the higher class and serve for relieving the driver primarily on long trips. For this purpose a desired traveling speed is preselected, and the traveling speed regulating device regulates the traveling speed through an adjusting member in correspondence with this preset. The adjusting member engages the gas pedal, the throttle flap, the fuel injection, etc.
Some operational conditions can occur, such as for example the downhill operation during descending on an incline, during which the adjusting member due to the displacing mass is regulated back to zero-abutment, or in other words to a position in which the throttle flap is closed. Therefore the case can occur, especially with steep inclines, that the vehicle is further accelerated due to its mass and exceeds the adjusted traveling speed. With automatic transmissions, also the undersired effect can occur that the transmission, due to a high rotary speed reached, is switched to the next higher gear which leads to a further increase in the traveling speed due to the drop of a transmission braking moment. The driver is therefore forced to press on the brake or engage other measures, which often leads to a switching-off of the traveling speed regulating device. The above described situations are undesirable and influence the comfort of the traveling speed regulation.